Battery cell design and method of its construction

Abstract

A compact, robust, multifunctional and highly manufacturable rechargeable battery cell is provided. The cell design dedicates minimal internal volume to inert components of the cell. This is accomplished, in part, by providing multiple functionalities to individual cell components.

1. An electrochemical device, comprising:
 a spirally wound electrochemical assembly having a sidewall and upper and lower faces, said electrochemical assembly comprising: 
 a terminal for making a connection external to the device; 
 a separator interposed between a positive electrode comprising a positive current collector having a layer of positive electroactive material deposited thereon, the current collector having uncoated edge portions, and a negative electrode comprising a negative current collector having a layer of negative electroactive material deposited thereon, the current collector having uncoated edge portions, wherein the uncoated edge portions of the positive and negative electrodes are on opposite faces of the spirally wound assembly; 
 a plurality of conductive tabs in electrical contact with the uncoated portions of at least one of the positive and negative current collectors and extending outward from the current collector, wherein the tabs of the at least one of the positive and negative current collectors are spaced apart from one another such that the conductive tabs are located within a predetermined region of the face of the spiral winding so that during assembly the tabs extending from one of the at least one of the positive and negative current collectors intersect when folded towards the center of the spirally wound face, and fold into a second opposing region of the face of the spiral winding; and 
 a foldable terminal extension that secures the tabs from the one of the at least one of the positive and negative current collectors to form an electrical connection with the terminal, such that the foldable terminal extension and the tabs that are secured by the terminal extension lie flat with respect to the spiral winding. 
 
     
     
       2. The device of  claim 1 , wherein the device includes tabs for both positive and negative electrodes. 
     
     
       3. The device of  claim 1 , wherein the tabs are aligned within 100 degrees of one another on the face of the spiral winding. 
     
     
       4. The device of  claim 1 , wherein the tabs are aligned within 90 degrees of one another on the face of the spiral winding. 
     
     
       5. The device of  claim 1 , wherein the tabs are of different lengths. 
     
     
       6. The device of  claim 5 , wherein tab length is selected so that the ends of the tabs are aligned when folded. 
     
     
       7. The device of  claim 1 , wherein the device comprises four tabs for each electrode. 
     
     
       8. The device of  claim 1 , wherein the device comprises 3 to 10 tabs per electrode. 
     
     
       9. The device of  claim 1 , wherein the device comprises 1 tab per 200 cm 2  area of electrode. 
     
     
       10. The device of  claim 1 , wherein the terminal extension is in the form of a connecting strap. 
     
     
       11. The device of  claim 5 , further comprising a case that houses the spirally wound electrochemical assembly. 
     
     
       12. The device of  claim 1 , wherein the spirally wound electrochemical assembly is disposed in a metal can, the metal can comprises,
 a side wall defining first and second open ends; 
 a first metal end cap comprising aluminum, the first metal end cap disposed at the first open end of the side wall and having an internal surface and an external surface, the external surface of the first metal end cap is nickel-plated; 
 the terminal being in the form of a plate comprising nickel soldered to the external surface of the first metal end cap; and 
 a second metal plate disposed at the second open end of the side wall. 
 
     
     
       13. The device of  claim 1 , wherein the spirally wound electrochemical assembly is disposed in a cylindrical container housing having at least one opening;
 an end cap is disposed to cover the opening, the end cap defining a centrally-located fill hole; and 
 a plug is sealingly disposed in the centrally located fill hole. 
 
     
     
       14. The device of  claim 13 , wherein the plug serves as the terminal for connecting the device to the external connection. 
     
     
       15. The device of  claim 13 , wherein the plug comprises a sealing member sealingly disposed in the fill hole and a deformable metal insert capable of pressing against the sealing member to form a liquid impermeable seal. 
     
     
       16. The device of  claim 13 , wherein the centrally located fill hole comprises a feedthrough inlet fittingly disposed within the hole and connected to the interior of the device. 
     
     
       17. The device of  claim 16 , wherein the feedthrough inlet comprises:
 a rivet having a substantially flat head defining a hole corresponding to the fill hole and extending over a portion of an external face of the end cap and a hollow stem extending into the interior of the cylindrical container; and 
 a rivet backing disposed at an internal face of the end cap and engaged with a distal portion of the rivet stem. 
 
     
     
       18. The device of  claim 17 , wherein the fill hole further comprises:
 an upper insulating member disposed between the rivet and the end cap and defining a hole corresponding to the fill hole; and 
 a lower insulating member disposed between the end cap and the rivet backing. 
 
     
     
       19. The device of  claim 1 , wherein the terminal extension has an overlapped portion, such that ends of the tabs from the one of the at least one of the positive and negative current collectors are held within the overlapped portion. 
     
     
       20. The device of  claim 19 , wherein the terminal extension and the tabs that are held are foldable from a first position extending along an axial direction of the spiral winding to a second position where the overlapped portion lies flat with respect to the spiral winding. 
     
     
       21. The device of  claim 20 , further comprising pieces of tape that cover portions of the plurality of conductive tabs and adjacent areas of the uncoated portions of the at least one of the positive and negative current collectors. 
     
     
       22. The device of  claim 21 , wherein the terminal extension secures the tabs by one of an ultrasonic and resistance weld. 
     
     
       23. The device of  claim 1 , wherein the terminal extension has a rectangular shape with planar opposing surfaces that respectively face inwardly and outwardly along an axial direction of the spirally wound electrochemical assembly.